In the production of a shaped article of gypsum, the amount of water theoretically required for the reaction of hardening by hydration of hemihydrate gypsum is about 20% by weight of the weight of the hemihydrate gypsum. With this theoretical amount of water, however, the act itself of mixing the hemihydrate gypsum with the water is difficult to carry through. For the purpose of homogeneously mixing them and enabling the resultant mix to retain satisfactory slowability, it has been necessary to use water in a much larger amount.
The amount of water used in the process of production has bearing on the strength which the shaped article of gypsum acquires after it hardens; the shaped article of gypsum using a larger amount of water is conspicuously inferior in strength and durability to the shaped article of gypsum using water in the theoretical amount. Studies are now under way in search of a method which allows a decrease in the amount of water to be mixed with gypsum during the course of production of a shaped article of gypsum, only to encounter the problem mentioned above. In the circumstances, the desirability of perfecting a shaped article of gypsum which possesses ample strength and durability and allows easy blending during the course of production and a method for the production of this shaped article of gypsum has been finding enthusiastic recognition.